1. Field of the Invention
The present invention relates to a motor and a panel meter incorporating the motor.
2. Description of the Related Art
In recent years, a stepping motor has been used as an actuator, in a movable section of a panel meter in an automobile such as a speed meter and a tachometer. Stepping motors used for the panel meter of the automobile or the like have been disclosed, for example, in Unexamined Japanese Patent Application KOKAI Publications No. H5-161333 and H9-222338.
The stepping motor is a component of the movable section of the panel meter and is arranged between a display board having a scale to indicate a measured amount or value and a printed circuit board (PCB). An indicating needle is attached to one end of a rotary shaft that the stepping motor has.
In order to improve the visibility of the panel meter, it is necessary to guide (lead) light to the indicating needle and the display board having a scale with characters and so forth. Conventionally, in order to improve the visibility of the panel meter, and especially of the indicating needle, for example, a luminous element is arranged on the PCB, and an optical path is formed such that a light conductive plate made of a light-transmissible resin such as an acrylic resin is arranged between the back surface of the display board. Light emitted from the luminous element as a light source is guided from the back of the display board to the indicating needle so as to illuminate the indicating needle and the display board.
The conventional panel meter uses light conductive plate to guide the light to the indicating needle, etc. for obtaining a good visibility. However, using the light conductive plate results in a complicated structure of the panel meter. Besides, it is difficult to guide the light emitted in a relatively wide range to the indicating needle efficiently by the structure described above.
Furthermore, since the dimension, especially the thickness of the light conductive plate must be taken into consideration when designing the panel meter, the degree of freedom in designing is limited.